For the purposes of this study, as a core lab coordinating center, we will be performing P31 MRS core lab analyses; hormone core lab analyses; lipid core lab analyses; glucose, insulin and HOMA core lab analyses; exercise stress test/Holter monitor core lab analyses; brachial artery reactivity test core lab analyses; full study data analyses for manuscript preparation and the writing and submission and publication of manuscript.

Coronary endothelial cell dysfunction which results in vasoconstriction is a mechanism responsible for signs and symptoms of ischemia (decreased blood flow to the heart) in patients. Preliminary evidence in women suggests that estrogen levels may be involved. Women have more evidence of a decreased blood supply to the heart muscle even when they have normal coronary arteries compared to men. This is called Syndrome X. While animal and human work demonstrates that low estrogen levels make endothelial dysfunction worse, and that estrogen replacement eliminates this effect, this has not been evaluated in women suffering from Syndrome X.

The impact of hormone replacement therapy on decreased blood flow to the heart muscle in female patients with normal coronary arteries (Syndrome X) is unknown.

The primary purpose of the WISE Ancillary FemHRT study (IRB # 2779) was to evaluate the effect of estrogen replacement therapy with FemHRT in postmenopausal women with Syndrome X on: 1) inducible myocardial ischemia, measured by P-31 metabolic MR spectroscopy, and 2) endothelial dysfunction, measured by brachial artery reactivity measurement. Secondary outcomes of interest were to assess the effect of FemHRT on blood lipids hormone, glucose and insulin levels.

For the purposes of this study, as a core lab coordinating center, we will be performing the following analyses on tapes, specimens, and data PREVIOUSLY collected as part of the original Ancillary WISE FemHRT Study (CSMC IRB#2779): P31 MRS core lab analyses; hormone core lab analyses; lipid core lab analyses; glucose, insulin and HOMA core lab analyses; exercise stress test/Holter monitor core lab analyses; brachial artery reactivity test core lab analyses; full study data analyses for manuscript preparation and the writing and submission and publication of manuscript. There is no active recruitment of subjects or samples, specimens or data that is currently and actively being collected. The analyses is retrospective on previously collected samples gathered from the WISE Anc. FemHrt study.

Inclusion Criteria:

• Previously collected samples gathered from the WISE Anc. FemHrt study.